In-depth study of the pathobiology of early lung development and elucidation of factors that regulate and control growth and differentiation require appropriate models in which the developmental events can be observed and manipulated. Primary explant cultures of lung tissue are appropriate models since they undergo changes mimicking in vivo maturation and are responsive to hormones. The Tissue Culture Core Laboratory, has a well established history for studies utilizing the explant model, and has recently established the lung bud organ culture model. The explant model which has been extensively employed to study human fetal lung development is a particularly useful model for studies of maturation of the surfactant system and Type II epithelial cells, but has not been fully explored as a model of mesenchymal differentiation. The lung bud organ culture provides an earlier model for embryonic development of the lung epithelium and mesenchyme, and allows study of molecular events from early branching through epithelial cell maturation. Primary enriched cell populations (epithelial, fibroblast) isolated from the explants and pulmonary cell lines are useful for transduction, transfection and other approaches to study of altered gene expression. The specific aims of this Core are to support the research goals of Projects I-IV as follows: a. Prepare and maintain primary explant cultures of fetal lung as needed (human, rat and bovine). b. Prepare and maintain mouse lung bud cultures. c. Prepare enriched isolated cell populations (Type II cells, fibroblasts) from fetal human rat and bovine lung for short term study. d. Provide monolayer cultures of pulmonary cell lines upon request. 2. Provide all Projects with access to necropsy lung samples from human infants with suspected BPD, or S-B deficiency as well as control donor lung from transplants. These samples will originate via the Clinical Tissue Bank of Project V, and will be a available for culture and immunohistochemical studies. 3.. Co ordinate and organize integrated use of all culture setups between Projects, to facilitate timely data collection for all Projects, optimize use of the tissue resources, and promote interaction and data correlation between Projects. 4. Act as a resource for training fellows and technical personnel, providing both technical training and scientific expertise in utilization and manipulation of the primary culture models. 5. Carry-out fixation/embedding of tissues for microscopy, and certain other manipulations of lung cultures as needed. 6. Serve as a center for interaction and collaboration between all SCOR grant investigators to facilitate exchange of ideas and experimental findings.